A HISTORY OF SCIENCE 



studies, as yet unpublished, we shall be able to see the 

 whole difference which exists between the two meth- 

 ods the uncertainty of the one and the certainty of 

 the other. That which we announce has, moreover, 

 the very great advantage of resting upon the existence 

 of a poison vaccine cultivable at will, and which can 

 be increased indefinitely in the space of a few hours 

 without having recourse to infected blood." 8 



This announcement was immediately challenged in 

 a way that brought it to the attention of the entire 

 world. The president of an agricultural society, real- 

 izing the enormous importance of the subject, proposed 

 to Pasteur that his alleged discovery should be sub- 

 mitted to a decisive public test. He proposed to fur- 

 nish a drove of fifty sheep half of which were to be 

 inoculated with the attenuated virus of Pasteur. Sub- 

 sequently all the sheep were to be inoculated with viru- 

 lent virus, all being kept together in one pen under pre- 

 cisely the same conditions. The "protected" sheep 

 were to remain healthy ; the unprotected ones to die of 

 anthrax; so read the terms of the proposition. Pas- 

 teur accepted the challenge ; he even permitted a change 

 in the programme by which two goats were substituted 

 for two of the sheep, and ten cattle added, stipulating, 

 however, that since his experiments had not yet been 

 extended to cattle these should not be regarded as 

 falling rigidly within the terms of the test. 



It was a test to try the soul of any man, for all the 

 world looked on askance, prepared to deride the maker 

 of so preposterous a claim as soon as his claim should be 

 proved baseless. Not even the fame of Pasteur could 



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